Discover mobile devices
To discover devices connecting to your Exchange server that are not currently being managed, Modern Device Management uses mobile device connection information from the Exchange mail server. Agentless discovery doesn't require any communication with the actual mobile device. Only mobile devices that have connected to a corporate mail box can be discovered.
You must have the Exchange information configured in order to connect to the Exchange server and discover devices. For information on configuring the connection to the Exchange server, see Configure an Exchange server connection.
To discover mobile devices
1.Click Tools > Modern Device Management > MDM configurations > Additional Device Discovery > Exchange ActiveSync.
2.Confirm that the server settings are correct and click Discover now, or click Schedule discovery to create a scheduled task for device discovery.
Once the information is retrieved from the Exchange server, the devices appear in the device inventory.